1. Field of the Invention
The present invention relates to a semiconductor device and a photomask, particularly to a semiconductor device having a shared contact hole that reaches both a gate electrode layer and an impurity region and a photomask that is used in patterning of the gate electrode layer.
2. Description of the Background Art
For example, Japanese Patent Laying-Open Nos. 09-321152, 2004-273642, 2004-273972, and 2004-327796 disclose the semiconductor device having the shared contact hole that reaches both the gate electrode layer and the impurity region.
Usually the shared contact hole has a tapered shape in section in which an opening diameter is decreased from an opening end toward a deep position. Therefore, when an etching film such as an insulator is etched to make the shared contact hole, an etching area of the etching film is reduced with the progress of etching. The reduction of the etching area obstructs the progress of the etching, resulting in a conductive problem such as an opening defect in which the shared contact hole does not reach an active layer (impurity region).
For example, during the etching for making the shared contact hole, the etching is obstructed in the middle of the etching by a projection of a sidewall spacer located in a gate electrode layer sidewall. Therefore, in a planar view, unless a distance from an end (end that is not etched by the etching in making the shared contact hole) of the sidewall spacer to an edge portion in a long-side direction of the shared contact hole is largely ensured, a residue is generated in a process of etching a liner nitride film on the sidewall spacer, thereby generating the opening defect.